1. Field of the Invention
This invention relates to the field of siding panel assemblies and more particularly to siding panels which are attached to a building to form the exterior surface thereof.
2. Description of the Prior Art
Building siding units have previously been formed from thin plastic sheet material which can have a variety of colors and which is substantially maintenance free and of long life. Also, siding units have been made of metal sheets. However, siding units formed from plastic or metal sheet material is subject to expansion and contraction which occurs with changes in ambient temperature. Expansion of the building siding units between nailing points will cause buckling and distortion of the thin sheet material. The siding unit must be designed so as to compensate for the varying rates of expansion and contraction regardless of the tightness of the fasteners which secure the siding unit to the building.
Siding units must be securely fastened to the building structure, yet be loose enough to allow for normal expansion and contraction without distorting the siding units. Driving nails with a hammer requires skill and conscious effort to ensure a properly driven fastener. Experience has shown highly variable results and generally overdriven fasteners. Also variable results in achieving a properly driven fastener are found even with pneumatic guns because of varying density in the underlying substrate.
Various means have been tried in the past to provide for the expansion and contraction of the siding unit. For example, U.S. Pat. No. 4,435,933 describes rigid clips, having an upper hanger portion and a lower channel formed to grasp the common elongate protrusions formed along the top edge of extruded vinyl siding, which support the siding while permitting it to expand and contract freely with changes in temperature. U.S. Pat. No. 3,552,078 illustrates a building siding unit attachment arrangement which requires a separate attachment strip to engage a retainer means of a face panel to support the panel and to permit free relative longitudinal movement between the attachment strip and the panel. U.S. Pat. No. 3,504,467 illustrates a siding panel which has a fastening flange of concave configuration in cross section to prevent and discourage the overdriving of the nail or securing means when installing the panel. The elimination of overnailing coupled with the elongated configuration of the nailing apertures allows the siding panels to slide on nails without undue restriction in their horizontal movement after installation.